CN101452200B - Lens stray light detecting system - Google Patents

Abstract

The invention provides a lens stray light detection system, which includes a stray light analysis light source, an image sensor, a laser light source, a laser focusing device, a wavefront sensor, a processor, an object distance adjustment device and a Image sensor mobile device. The object distance adjusting device is used to change the distance between the focal point of the laser and the wavefront sensor. The image sensor moving device is used to move the image sensor to the corresponding focus position of the lens for different object distances. The processor includes: an object distance setting module, used to set the required object distance; an object distance acquisition module, used to obtain the object distance from the laser focus to the wavefront sensor; an object distance adjustment module, used to control the object distance adjustment device; The focus control module is used to control the moving device of the image sensor; the stray light analysis module is used to analyze the stray light condition of the image sensor.

Description

Lens stray light detection system

technical field

The invention relates to a detection system for detecting lens stray light.

Background technique

With the continuous development of digital technology, digital cameras have been widely used by people, especially in recent years, portable electronic devices such as mobile phones and PDAs (Personal Digital Assistants, personal digital assistants) are also rapidly developing in the direction of high performance and multifunctionality. The combination of cameras and these portable electronic devices has become the key to the development of mobile multimedia technology. While people's demand for digital cameras continues to grow, the requirements for digital camera performance are also getting higher and higher.

However, after the lens is assembled, due to the dimensional tolerances of the materials used, surface roughness, surface reflection and refraction, the feasibility of matching each material part, assembly procedures and capabilities, etc., unexpected complications occur during the design evaluation. astigmatism.

The existing stray light detection can only detect the stray light effect of the lens at a fixed object distance. This detection method is difficult to detect the impact of stray light on the lens when the lens is at different focus positions at different object distances.

Contents of the invention

In view of this, it is necessary to provide a system that can detect the influence of stray light of the lens on different focus positions.

A lens stray light detection system, which includes a stray light analysis light source, an image sensor, a laser light source, a laser focusing device, a wavefront sensor, a processor, an object distance adjustment device, an image sensor device shifter and a lens switching device. The laser light source and the laser focusing device are located on the optical path of the laser light source. When focusing, the lens and image sensor are located on the optical path of the laser; when testing stray light, the lens and image sensor are located in the stray light analysis light path of the light source. The object distance adjustment device is used to change the distance between the focal point of the laser and the wavefront sensor, and the image sensor moving device is used to move the image sensor to the corresponding focus position of the lens for different object distances, so The lens switching device is used to place the lens and the image sensor on the laser light path or the light path of the stray light analysis light source, and the processor includes: an object distance setting module, which is used to set the required object distance; an object distance acquisition module, It is used to calculate the wavefront curvature radius of the laser as the object distance according to the output signal of the wavefront sensor and use the wavefront reconstruction algorithm; the object distance adjustment module is used to control the object distance adjustment device according to the set object distance; focusing/ The test switching module is used to control the lens switching device and control the opening and closing of the laser light source and the stray light analysis light source; the focal length control module is used to control the moving device of the image sensor according to the clarity of the image sensed by the image sensor; the stray light The analysis module is used for analyzing the stray light condition of the lens of the image sensor under the stray light analysis light source.

Description of drawings

FIG. 1 is a hardware architecture diagram of a lens stray light detection system for focusing provided by the present invention.

Fig. 2 is a functional block diagram of a processor of the lens stray light detection system for focusing provided by the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings.

Please refer to FIG. 1 for a lens stray light detection system 100 provided by the present invention. It includes a stray light analysis light source 10, an image sensor 11, a laser light source 12, a laser focusing device 13, a wavefront sensor 14, a processor 15, an object distance adjustment device 16, an image sensor A moving device 17 and a lens switching device 18 .

In order to realize the focus adjustment of the lens 90 in a wide range, a collimator 20 or an adjustable lens group 21 can be added separately between the laser focusing device 13 and the wavefront sensor 14 , or both can be added. In this embodiment, a collimator 20 and an adjustable lens group 21 are added.

The lens 90 and the image sensor 11 are located on the lens switching device 18 , and the lens switching device 18 is used to place the lens 90 and the image sensor 11 on the laser light path or the light path of the stray light analysis light source 12 . When the image sensor 11 needs to be set at the imaging focus of the lens 90 for a certain object distance, the lens switching device 18 places the lens 90 and the image sensor 11 on the laser light path, and simultaneously moves the wavefront sensor 14 out Laser optical path; when stray light testing is required, the lens switching device 18 places the lens 90 and image sensor 11 on the optical path of the stray light analysis light source 10, moves the wavefront sensor 14 back to the laser optical path, and opens Light source for stray light analysis. The lens switching device 18 can switch the positions of the lens 90 , the wavefront sensor 14 and the image sensor 11 by means of a turntable or a slide rail.

The laser light source 12, the laser focusing device 13, the collimator 20 and the adjustable lens group 21 are located on the same optical path.

In this embodiment, the laser light source 12 is a laser diode, and other lasers may also be used. The laser focusing device 13 is a pinhole or a focusing lens for imaging the laser. In this embodiment, a light barrier with a small hole through which the laser can be imaged. The wavefront sensor 14 is a Hartmann wavefront sensor. The processor 15 calculates the offset between the center of gravity of the sub-aperture converging light spot and the center of gravity in the two-dimensional direction from the Hartmann wavefront sensor, obtains the wavefront slope of the sub-aperture from the focal length and the offset of the sub-aperture, and then The detection data of the wavefront is reconstructed by the reconstruction algorithm, and the radius of curvature of the wavefront is calculated, thereby calculating the virtual object distance of the laser beam. Described wavefront sensor 14 also can adopt self-reference wavefront sensor, and described processor 15 obtains wavefront information after performing a matrix operation according to the phase-shifting interferogram of the output of self-reference wavefront sensor, calculates wavefront radius of curvature, Thus, the distance in the direction of the laser light path between the focus point of the laser in the laser focus device and the wavefront sensor is calculated. In this embodiment, the wavefront sensor 14 is a Hartmann wavefront sensor.

The object distance adjusting device 16 is used to change the distance between the laser focus point and the wavefront sensor. It can change the distance between the collimator 20 and the laser focusing device 13 or the distance between the lenses in the adjustable lens group 21, or both can be adjusted to change the collimation of the laser light emitted by the laser light source 12. The radius of curvature of the laser wavefront of the instrument 20 and the adjustable lens group 21, thereby changing the distance between the focal point of the laser light and the wavefront sensor 14. In this embodiment, the image sensor moving device 17 adjusts the distance between the laser focusing device 13, the collimator 20, the laser focusing device 13 and the lenses in the adjustable lens group 21 along the direction of the laser light path. adjust.

The image sensor moving device 17 is used to move the image sensor 11 to the corresponding focus positions of the lens 90 for different object distances. In order to obtain the influence of the lens 90 on the stray light of different object distances, it is necessary for the lens 90 to focus on different object distances. In this embodiment, the image sensor moving device 17 moves the image sensor 11 to the focal point of the lens 90 for laser light with different object distances. The image sensor moving device 17 adjusts the distance between the lens 90 and the image sensor 11 in a threaded manner or a sliding rail manner. In this embodiment, a screw method is used.

Please refer to FIG. 2 for a functional block diagram of the processor. The processor 15 includes: an object distance setting module 150 , a focus/test switching module 151 , an object distance adjustment module 152 , a focal length control module 153 , an object distance acquisition module 154 and a stray light analysis module 155 . The object distance setting module 150 is used to set the required object distance. The focusing/test switching module 151 is used to control the lens switching device and control the opening and closing of the laser light source and the stray light analysis light source 10 . When the lens needs to be focused, the focus/test switching module 151 places the lens 90 and the image sensor 11 on the laser light path, and moves the wavefront sensor 14 out of the laser light path. When a stray light test is required, the focusing/test switching module 151 controls the lens switching device 18 to place the lens 90 and the image sensor 11 on the optical path of the stray light analysis light source 10, and move the wavefront sensor 14 to Back to the laser light path, and turn on the stray light analysis light source 10. The object distance obtaining module 154 is configured to calculate the wavefront curvature radius of the laser light as the object distance according to the output signal of the wavefront sensor 14 and by using the wavefront reconstruction algorithm. In this embodiment, the module 154 calculates the offset between the center of gravity of the sub-aperture converging spot and the calibration center of gravity in the two-dimensional direction, calculates the wavefront slope of the sub-aperture from the focal length and the offset of the sub-aperture, and then uses the reconstruction algorithm The detection data of the wavefront is reconstructed, the radius of curvature of the wavefront is calculated, and the virtual object distance of the laser beam is calculated. The object distance adjustment module 152 is configured to control the object distance adjustment device according to the set object distance. According to the difference between the measured object distance and the set object distance, the object distance adjustment module 152 calculates the laser focus device 13, the adjustment collimator 20, the laser focus device 13 and the lens in the adjustable lens group 21. The displacement in the direction of the laser light path. If a long object distance is required, the devices move the laser focus away from the wavefront sensor 14 along the optical path; if a short object distance is required, the devices move the laser focus close to the wavefront sensor 14 along the optical path. The focus control module 153 is configured to control the image sensor moving device 17 according to the clarity of the image sensed by the image sensor 11 . The module controls the distance between the lens 90 and the image sensor 11 according to the sharpness of the laser imaging on the image sensor 11 , so that the image sensor 11 is located at the focal point of the lens 90 at the object distance. The stray light analysis module 155 is configured to analyze the impact of the stray light of the image sensor 11 at the focal length on the lens 90 .

When the next test needs to be performed after completing one test, the process of determining the object distance, focusing and testing is performed again, and finally the test of the influence of stray light on the lens 90 at different object distances is completed.

The lens stray light detection system of the invention can make the lens focus on different object distances, and detect the stray light under different focusing conditions of the lens. In this way, the impact of stray light at different focal points of the test lens can be achieved, and the ability to detect lens stray light can be improved.

It can be understood that those skilled in the art can make various other corresponding changes and modifications according to the technical concept of the present invention, and all these changes and modifications should belong to the protection scope of the claims of the present invention.

Claims (7)

1. A lens stray light detection system comprising a stray light analysis light source and an image sensor, characterized in that the lens stray light detection system also comprises a laser light source, a laser focusing device, a wavefront sensor , a processor, an object distance adjustment device, an image sensor moving device and a lens switching device, the laser light source and the laser focusing device are located on the optical path of the laser light source, when focusing, the lens and the image sensor Located on the optical path of the laser, when testing stray light, the lens and image sensor are located on the optical path of the stray light analysis light source, and the object distance adjustment device is used to change the distance between the focal point of the laser and the wavefront sensor , the image sensor moving device is used to move the image sensor to the corresponding focus position of the lens for different object distances, and the lens switching device is used to place the lens and the image sensor in the laser light path or stray light analysis On the light path of the light source, the processor includes: an object distance setting module, used to set the required object distance; an object distance acquisition module, used to calculate the laser beam distance according to the output signal of the wavefront sensor and using the wavefront reconstruction algorithm. The radius of curvature of the wavefront is used as the object distance; the object distance adjustment module is used to control the object distance adjustment device according to the set object distance; the focus/test switching module is used to control the lens switching device and control the laser light source and stray light analysis light source. close; the focus control module is used to control the moving device of the image sensor according to the clarity of the image sensed by the image sensor; the stray light analysis module is used to analyze the stray light of the lens of the image sensor under the stray light analysis light source situation. 2. The lens stray light detection system according to claim 1, wherein the wavefront sensor is a Hartmann wavefront sensor. 3. The lens stray light detection system according to claim 1, wherein the wavefront sensor is a self-referencing wavefront sensor. 4. The lens stray light detection system according to claim 1, wherein the laser focusing device is a small hole or a focusing lens for imaging the laser. 5. The lens stray light detection system according to claim 1, further comprising a collimator and an adjustable lens group. 6. The lens stray light detection system according to claim 1, wherein the object distance adjusting device is used to move the laser focusing device along the laser optical path. 7. The lens stray light detection system according to claim 5, wherein the object distance adjustment device is used to move the collimator or the adjustable lens group or both along the laser light path.

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